Romans 11:12

‘And if their false step is the riches of the world, and their loss the riches of the Gentiles, how much more their fullness?'

For the false step of the unbelieving Jews in rejecting their Messiah, has resulted in riches for the world, because it has resulted in the Messiah being proclaimed more widely to the world so that the Gentiles have received the riches of His salvation. But at the same time it has caused loss to the unbelieving Jews as a result of their rejection (as being in God's eyes no longer Israel). It has resulted in riches for the Gentiles, because it has caused more emphasis to be laid on the conversion of Gentiles to the Messiah, but if this be so how much more will their restoration to full belief in the Messiah result in even greater riches for the world, as they once more join Israel and use their religious zeal in proclaiming the Messiah.

This idea of ‘spiritual riches' permeates this section. God has made known the riches of His glory on the vessels of mercy which He has beforehand prepared for glory (Romans 9:23). God is rich to all who call on Him whether Jew or Gentile (Romans 10:12). Now the fall of the unbelieving Jews has provided riches for the Gentiles, the riches of the glory that God purposes for His own, which are receivable by calling on Him in faith.

‘How much more their fullness.' This could be seen as referring to the unbelieving Jews coming to ‘a full knowledge of Christ', their Messiah, so that through their deeper understanding of the Scriptures they might increase the riches received by the Gentiles. We must ever remember that the Gentiles were relatively new to the Scriptures, and could not consult them with ease, whereas the Jews had been brought up to them from babyhood (see 2 Timothy 3:15). So once they have knowledge of the Messiah in their hearts through faith, what knowledge they could contribute, and what evangelists they will be!

Others see ‘fullness' as referring to ‘achieving their full number', with the idea being that the future would at some stage see an acceleration of the conversion of the Jews to a recognition of their Messiah. Compare ‘the fullness of the Gentiles' in Romans 11:25. But either way the point is that the conversion of many Jews to Jesus Messiah will be a good thing for God's people. What happened to Jerusalem later may well have caused many Jews to recognise that Jesus was the Messiah, because He had so clearly predicted it, and there have been other events through history which may well have resulted in conversions to Christ among the Jews. Their achieving their fullness does not necessarily require an end of age revival. It is just something that we can hope for. After all if there was only one more Jew elected to be converted, his conversion would bring Israel to its fullness, as in the case of the Gentiles. But Paul's attitude may certainly be seen as giving the impression of something special.